Grinding machine



Sept. 12, 1933. H. BLOOD GRINDING MACHINE Filed Nov. 16, 1931 gnucwfoz Harold I LlBlood Patented Sept. 12, 1933 UNITED STATES PATENT OFFICE The Heald Machine Company,

Worcester,

Mass., a corporation of Massachusetts Application November 16, 1931 Serial No. 575,253

8 Claims. (Cl. 5150) The invention relates to grinding machines and its particular utility is in connection with internal grinding machines for grinding the internal cylindrical or conical surfaces of sleeves, gears, bushings, ball races and thelike.

In the grinding of workpieces in automatic grinding machines of this type the grinding wheel is Withdrawn axially from the workpiece at the completion of'the grinding operation, to permit removal of the completed workpiece. As the axial separation usually occurs at a rapid rate of speed, unless the pressure of the grinding wheel against the surface of the workpiece be relieved, the grinding wheel leaves objectionable spiral scratches on the surface of the workpiece which detract from the smooth finished appearance. The separation also results in a bell mouthing effect on the workpiece since, as the grinding wheel is withdrawn from the bore, the area of contact between the grinding wheel and the surface of'the workpiece gradually diminishes in size. This decreasing area must support the entire pressure of the grinding wheel against the workpiece and accordingly the unit pressure on the surface being ground increases, with the result that the grinding wheel cuts deeper and deeper as the grinding wheel is withdrawn from the end of the bore of the workpiece providing a finished bore which is not perfectly cylindrical throughout. The principal object of the invention is to provide for withdrawal of the grinding wheel from the surface of the workpiece before the axial separation to avoid the above disadvantages.

Patent No. 1,816,082, granted July 28, 1931 to Heald and Guild, discloses a mechanism by which the grinding wheel is withdrawn laterally from the surface of the workpiece before the axial separation occurs in order to avoid the objectionable scratch or hell mouthed surface. The separation in this case as well as in Patent No. 1,826,178, issued to Kempton and Gallimore on October 6, 1931, is procured by axial movement of the crossfeed screw, the latter operating normally by rotation thereof to provide a feeding movement of tegral part of the crossfeed mechanism and in-.

volves a complicated mechanism for the crossfeed movement and the lateral separation. Another object of the invention is accordingly to provide for lateral separation of the grinding wheel from the workpiece independently of the crossfeed mechanism, and also to provide for the lateral separation by mechanism which may be mounted on a completed grinding machine.

According to the present invention, either the grinding wheel or the workpiece is arranged for 4 a crossfeed movement on the reciprocating carriage of the machine and the lateral separation is procured by movement of the other of. said members transversely of the machine in response to fluid under pressure which urges said member temporarily transversely to separate the grinding 0 wheel from the workpiece, the said member returning to original position when the fluid'pressure is relieved. Other and further advantages will appear from the following description taken in connection with the accompanying drawing in which:- a

Fig. 1 is a front elevation of a grinding machine embodying the invention.

Fig. 2 is a fragmentary section along the line 2-2 of Fig. 1.

Fig. 3 is a section through the valve which controls the lateral separation of the grinding wheel from the workpiece.

Fig. 4 is a wiring diagram.

Like reference characters refer to like parts throughout the different figures.

Referring first to Fig. 1, an internal grinding machine is shown having the reciprocatory table or carriage 1 ordinarily provided in such a machine. Either the grinding wheel or the workpiece to be ground may be carried on the table 1, andthe reciprocation of the latter is utilized in either case to produce a relative traversing movement between the grinding wheel and the 5 workpiece. In the construction shown, the table 1 supports and carries a wheelhead 2, while the workpiece which is to be operated upon is held in the workhead 3, the latter being carried by a bridge 4 which spans the slideways provided by the machine frame for the longitudinal back and forth movement of the table 1. The grinding wheel 5 is carried on a spindle 6 which is suitably journaled in the wheelhead 2 and which is rotated in any suitable manner as by the incorporation of an electric motor in the wheelhead, the spindle 6forming' an integral extension of the armature shaft of the motor. The workpiece is mounted in a suitable workholding member 7 carried by a spindle journaled in the workhead 3, said spin- Taylor.

than the spindle 6, by a belt drive not shown.

The reciprocation of the table 1 to cause the rotating grinding wheel 5 to make the required internal traverse of the rotating workpiece may be imparted in any well known manner as by the'use of fluid pressure controlling and reversing mechanism as described in U. S.Letters Patout No. 1,582,468, granted April 27, 1926to Heald.

and Guild. Such mechanism is well known; it is sufiicient to note for present purposes that the driving means employed for the reciprocation of the table 1, be it hydraulic drive, gear drive, or

any other type, procures the reversal of the table at each end of the normal working stroke by the use of spaced adjustable dogs 8 and 9 carried by the table 1 and adapted alternately to engage and move a reversing member 10, which latter during the grinding operation, when the wheel 5 is moving back and forth within the workpiece 6, is situated between the two dogs 8 and 9 in position to be struck alternately by said dogs and by resultant movementfirst in one direction and then in the other effects reversal of the travel of the table 1.

The orossfeed movement between the work and the grinding wheel to feed the grinding wheel against the surface being ground is procured in this machine by lateral movement of the wheel head, on the table 1, in the manner disclosed in Patent No. 1,682,673, granted August 28, 1928 to The wheelhead is mounted on a crossslide, not shown, which is adapted to have a transverse movement on the reciprocatory table 1, and movement of the cross-slide is secured by rotation of a crossfeed screw 11, the latter being suitably connected to the cross-slide. As clearly disclosed in the above cited Taylor patent, rotation of the crossfeed screw for the crossfeed said screw. In this manner the rotation of the crossfeed screw and .thus the crossfeed movement of the grinding wheel is responsive to the reciprocatory movements of the table 1.

At the end of the grinding operation, the grinding wheel is withdrawn axially of the workpiece in response to mechanism of the type shown in the above-mentioned Taylorpatent. Referring to 1, the crossfeed screw 11 carries on the forward end thereof a hand wheel 15, on which is mounted a cam 16, Fig; 4, which latter, during the progress of the grinding operation engages an adjusting screw 17 carried by one end-of r. pivotally mounted lever 18, Fig. 4, to rock said lever. The rocking movement of the lever occurs just as the workpiece reaches predetermined finished size, and procures axial withdrawal movement of the grinding wheel to separate said wheel from the workpiece. Referring to Fig. 4,

the pivotally mounted lever 18 carries; on the end remote from the screw 17, a contact point 19 which, in response to the rocking movement ofsaid lever, is moved into engagement with a stationary contact member 20 to close the circuit through an electromagnet 21. As shown by the wiring diagram, electrical current may be supplied by a continuously *driven generator 22; one

dle being rotated, desirably at a slower speed terminal of this generator is grounded at 23 and the other terminal is connected by a lead 24 to one terminal of the electromagnet 21, the other terminal of the electromagnet being connected by a lead 26 to the stationary contact 20. The contact 19 on the lever 18 is grounded at 27 through said lever and a lead 28 connecting said lever to said ground. Engagement of the contacts 19 and 20, in response to the rocking of lever 18 thus energizes the electromagnet 21, causing attraction of an armature member 29 and the consequent elevation of its attached lever arm 30, these parts being pivoted on a shaft 31' on the front of the frame.

The elevation of the lever arm procures axial separation of the grinding wheel from the workpiece. Referring to Fig. 1, the left hand reversing dog 9 is pivoted to its carrying block 32 and normally rests by gravity in a position to engage table being brought to a full stop by any suitable means as, for example, the means shown in the aforesaid patent to Heald and Guild, No. 1,582,468.

The above described mechanism is all old and .well known in the art and of itself forms no part of the present invention, the latter involving the attainment in connection with such orsimilar grinding machine instrumentalities of the novel and useful results hereinbefore setforth.

.According to the present invention, the workhead carried on the bridge 4 spanning the table 1 is movedtransversely in response to fluid under pressure to procure a lateral separation of the wheel relative to the workpiece. To this end, an upright member 33 has a base 34 securely fastened to the base of the machine .by screws 35 so that the upper end of said member 33 is spaced laterally from the bridge, as best shown in Fig. 2. The upper end of said member 33 is provided with a cylindrical bore 36 which receives a piston 37, the outer end 01' which normally rests lightly against the front surface of the bridge. However,when fluid under pressure is admitted to the inner end of the bore 36 of the member 33 through a port '38, the piston 3'? is forced against the bridge with sufficient pressure to spring the bridge carrying the workhead transversely of the machine to separate the surface of the workpiece being ground laterally from the grinding wheel whereby the wheel is taken out of contact with the work as said wheel is withdrawn.'- The bridge returns to its original normal position upon release of the fluid pressure by the resiliency of the material of the base and bridge.

The lateral separation of the workpiece from the grinding wheel, procured by thefluid under pressure, as above set out, occurs-just as the workpiece reaches predetermined finished size, and before the axial separation of the grinding wheel the armature member 29 carries, in addition to the lever arm 30, a depending lever arm 39 integral therewith, and the lower end of the arm 39 engages the extending end of a valve plunger slidable in the valve casing 41 shown in section in Fig. 3. Fluid from a fluid pump 42, which provides fluid under pressure for reciprocating the table 1 is directed through a pipe 43 to an inlet port 44, Fig. 3, of the valve casing 41, which latter also provides an exhaust port 45 and an outlet port 46 connected by a pipe 47 to the port 38 for the bore 36. The valve plunger 40 is normally in the position shown in Fig. 3 in which fluid connection is provided between the outlet port 46 and the exhaust port 45, so that no pressure is exerted on the inner end of the piston, and the bridge at this time is in its normal position. When the workpiece reaches predetermined finished size and the electromagnet 25 is energized, the depending lever arm 39 is rocked counterclockwise to move the plunger 40 to the right and'provide fluid connection between the inlet port 44 and the outlet port 46 which is connected to the bore 36. Fluid under pressure is thus admitted to the bore 36 carrying the piston 37 urging the piston against the bridge and springing the bridge, as above pointed out, sufficiently to separate the workpiece laterally from the grinding wheel. When the engagement of the two contacts 19 and 20 is broken in order to release the armature of the electromagnet 21, the valve plunger is returned to, the position shown in Fig. 4 and the bridge returns to its normal position, the fluid from the bore 36 exhausting through the exhaust port 45. The armature 29 is released at the end of the grinding operation by manual retraction of the crossfeed movement which withdraws the cam 16 from engagement with the screw 17.

From the foregoing it will be apparent that the lateral separation of the workpiece from the grinding wheel occurs prior to the axial separation of the wheel from the work since the valve plunger40 is moved while the upwardly extending lever arm is between the dogs 8 and 9 and out of engagement with the dog 8, before said arm engages said reversing dog 8 to procure the axial separation of the grinding wheel from the workpiece. The lateral separation is. procured by moving the workhcad transversely of the machine temporarily by fluid under pressure, the workhead being resiliently returned to normal position. It will be noted that the lateral separation occurs independently of the orossfeed movement; in the embodiment above disclosed, the crossfeed is procured by transverse movement of the grinding wheel and the lateral separation of the wheel and workpiece is procured by transverse movement of the workhead. The mechanism for procuring the lateral separation is clearly adaptable to a completed grinding machine in which no means for lateral separation have been provided.

I claim:

1. Ina grinding machine, abase, agrinding wheel and a workholder thereon, means to procure a crossfeed movement of the grinding wheel relative to a workpiece in the workholder, means to separate said wheel axially from said workpiece during the grinding operation, and means to effect a lateral separation of said wheelhead and workpiece independently.of the crossfeed means during the axial separation by a distortion of the base.

2. In a grinding machine, a base, a grinding wheel member and a workholding member thereon, a cross-slide supporting one of said members, means to feed said cross-slide to effect a crossfeed movement between said grinding wheel member and a workpiece in said workholding member, means to separate said grinding wheel member and workpiece axially, and means to move one of said members laterally to procure a lateral separation of the grinding wheel member and workpiece during said axial separation, independently of said cross-slide and said feeding means, bya temporary distortion of the base inresponse to fluid under pressure.

3. In a grinding machine, a base, a grinding wheel and a workpiece thereon, a cross-slide supporting one of said members for a crossfeed movement between said members, and means governed by the progress of the grinding operation to procure a lateral separation of said members independently of said cross-slide by temporary distortion of the base of the machine in response to fluid under pressure.

4. In a grinding machine, a base, a grinding wheel, and a workpiece thereon, crossfeed mechanism for procuring the crossfeed movement between said members, and means to procure a relative lateral movement between said members independently of said crossfeed mechanism by a distortion of the base.

5. In a grinding machine, a grinding wheel and a workholder, crossfeed mechanism ,for procuring a crossfeed movement between said members,

means governed by the progress of the grinding operation to procure an axial separation of said members, and means to procure a lateral separation of said members independently of the crossfeed mechanism during the axial separation.

6. In a grinding machine, a base, a grinding wheel and a workpiece thereon, said members having predetermined movements relative to each other on the base, and means to procure a relative lateral movement between said members by a temporary distortion of the base.

'7. In a grinding machine, a base, a grinding wheel and a workpiece thereon, said members having predetermined movements relative to each other on the base, and means to procure a relative lateral movement between said members by a temporary distortion of the base, in response to fluid under pressure.

8. In a grinding machine, a grinding wheel and a workholder, crossfeed mechanism for procuring a crossfeed movement between said members, and means governed by theprogress of the grinding operation for procuring a lateral separation between said members independently of the crossfeed mechanism.

HAROLD L. BLOOD.

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